1. Field of the Invention
This invention relates to an integrated circuit device, more particularly a three-dimensional integrated circuit device.
2. Description of the Related Art
In general, an integrated circuit (IC) device has an equivalent circuit as shown in FIG. 1. A conventional IC device includes a main circuit 12, a protective circuit 13, and a solder pad unit 14. The main circuit 12 may be a memory or a logic circuit which can perform logic operation. The protective circuit 13 is normally formed around the main circuit 12 to protect the main circuit 12. The solder pad unit 14 is electrically connected to the protective circuit 13 to transmit an external electric signal. The protective circuit 13, based on the position thereof and the design of the IC device, may protect the main circuit 12 from electrostatic damage, may serve as a buffer circuit, or may limit a current passing to the main circuit 12.
A conventional IC device shown in FIG. 2 includes a substrate 11, the main circuit 12 formed on a central portion of the substrate 11, the protective circuit 13 formed on a peripheral portion of the substrate 11 to surround the main circuit 12, and a solder pad unit 14 electrically connected to the main circuit 12 and the protective circuit 13. Because the main circuit 12 and the protective circuit 13 are formed on the same substrate 11, the main circuit 12 and the protective circuit 13 should be spaced apart from each other by a predetermined spacing (S) so as to prevent the main circuit 12 from being adversely affected by a pulse current in the protective circuit 13. The pulse current may be generated from external charges or residual electrostatic charges in the protective circuit 13. Besides, the main circuit 12 may be further provided with a parasitic element for protection against the pulse current from the protective circuit 13. However, if the pulse current passes through an amplifier in the main circuit 12 to produce an unexpectedly large current, it may result in overheating and failure of the IC device.
In order to prevent overheating and failure of the IC device, IC design rules have specified a spacing between the main circuit 12 and the protective circuit is with respect to IC devices having different dimensions, such as 0.13 micrometer, 65 nanometers, 45 nanometers, etc.
However, the IC devices are currently under the trend of miniaturization, and thus preservation of the spacing in the IC device has become a bottleneck in miniaturization of the IC devices.